Replace the 20 year old water heater. It's past its life span. They now make more energy effecient water heaters which will lower your utility bill. Put a blanket around the new water heater while you're at it.
A light period is a menstrual cycle that is shorter and/or lighter than a woman's regular period. Women should familiarize themselves with their menstrual cycle, how many pads or tampons they use, and how long their periods last to quickly detect any changes in their periods.
Thus, the definition of light is given by human physiology, but the other divisions of the electromagnetic spectrum are more arbitrary. The full range of wavelengths is known as the electromagnetic spectrum. Radio waves, by definition, have wavelengths from 1 millimeter to 1000 kilometers. As we mentioned above, the product of wavelength and frequency is the speed of the wave.